Jin-wook and Yoo-mi meet at a Gangwon-do resort and get caught up in a series of misunderstandings and accidents. Yoo-mi was charmed by Jin-wook’s sly and playful personality, and they unexpectedly spend the night together. However, Yoo-mi disappears in the morning, leaving Jin-wook feeling perplexed and irrationally angry.
Three years later, the two meet again when Yoo-mi becomes a nutritionist at the company cafeteria where Jin-wook works. It seems that once a playboy Jin-wook, has given up his carefree life and works at the company owned by his father. He has feelings for Yoo-mi and has kept her bra-pad as a memory of the night that they spent together. At first, he is strict towards her, though it classifies as reasons for being near her, he later confesses to her and agrees to wait for her.
Soon he founds out that he has a son, who is actually Yoo-mi’s mothers son from her second marriage. He feels that he has wronged her and warms up to her, as he seems to accept that it is his son. When Jin-wook’s father finds out, he is outraged. Hence, increasing the misunderstanding. Then enters a pretty girl, Joo Hye-ri (Jung Da-sol) who is deemed a “suitable” wife for Jin-wook. Yoo-mi’s writer friend, Jung Hyun-tae (Jae Young-kim), is shown to have a secret crush on her. With all drama revolving around main characters’ mothers, Cha Jin-wook and Lee Yoo-mi finally manage to keep their love strong, while also resolving their personal problems with their parents.
The drama ends with Hye-ri “traveling together” with Hyun-tae and Yoo-mi and Jin-wook attending Yoo-mi’s mother’s re-wedding and Jin-wook saying “Today is D-day. Do you know how much I’ve waited for this day?” and Yoo-mi replying “Me too.”